An intermediate transfer recording medium is conventionally used to form printed products by recording an image beforehand in a receptor layer and thereafter transferring the receptor layer to a transfer-receiving material. Because, in this receptor layer, the image is stored by a thermal transfer recording method using a thermal transfer sheet provided with a colorant layer, a high quality image can be formed depending upon the structural materials of the receptor layer. The intermediate transfer recording medium also allow the receptor layer to have superior adhesion to the transfer-receiving material and to be transferred to the transfer-receiving material very adhesively by interposing an adhesive layer. It is therefore preferably used in the case of using transfer-receiving materials which are so resistant to the transfer of colorants that a high quality image cannot be directly formed and which tend to fuse with colorant layers in a thermal transfer step.
FIG. 12 shows a illustrative sectional view of an example of a typical intermediate transfer recording medium. An intermediate transfer recording medium 101 comprises a substrate film 102 and a transfer portion 112 having at least a receptor layer 105. On the receptor layer 105, an image 106 is formed by thermal transfer using a thermal transfer sheet provided with a colorant layer. The transfer portion 112 with the image 106 formed on the receptor layer 105 is peeled from the substrate film 102 and transferred to a transfer-receiving material to form the objective image 106 on the transfer-receiving material.
The intermediate transfer recording medium 101 is provided with, for instance, a protect layer 104 to prevent deterioration of the image 106 which has been transferred to the transfer-receiving material, thereby improving each weather resistance and finger print resistance of the image 106 and the receptor layer 105. It is also provided with a peelable layer 103 to make it easy to peel the receptor layer 105 and other necessary layers from the substrate film 102. For instance, in an intermediate transfer recording medium 101 as shown in FIG. 12, a receptor layer 105 on which an image 106 is formed is transferred to a transfer-receiving material together with a protect layer 104 and a peelable layer 103. At this time, the receptor layer 105 and other necessary layers (hereinafter called "transfer portion 112") are peeled at the boundary between the peelable layer 103 and the substrate film 102 and are transferred to a transfer-receiving material.
The use of such an intermediate transfer recording medium renders it possible to transfer and form a high quality image with high resolution on a transfer-receiving material. Also, printed products can be made by writing and printing necessary matter such as a signature in advance on a transfer-receiving material and thereafter transferring the transfer portion, on which images such as characters and photographs are formed, from an intermediate transfer recording medium. Hence, the intermediate transfer recording medium may be preferably used for producing printed products including identification cards such as passports, credit cards, ID cards, and the like.
It is required for printed products such as passports and credit cards as aforementioned to give security, specifically, high reliability and safety to resist forgery and falsification. Therefore, various ideas have been developed to resist forgery and falsification made by copying.
The applicant of the present invention has filed with the Japanese Patent Office an application for patent on an intermediate transfer recording medium provided with a hologram pattern, micro-characters and the like in its transfer portion and on a printed product obtained by transferring the transfer portion to a transfer-receiving material to prevent forgery and falsification of printed products such as passports and credit cards. This application is Japanese Patent Application No. H10 (1999)-185354, which was not open to public on the priority date of the application of this case. According to the invention, the hologram pattern and the micro-characters formed on the transfer portion are transferred to the transfer-receiving material together with an image thereby making it difficult to forge and falsify the images such as characters and a photograph of face formed on a printed product, giving high reliability and safety.
In the invention of Japanese Patent Application No. H10 (1999)-185354, preferably the transfer portion has a hologram layer and micro-characters are formed in the hologram layer. It is also preferable that the micro-characters be formed by embossing processing. When micro-characters are formed in the hologram layer, it is extremely difficult to forge. Moreover, when the micro-characters are formed by embossing processing, the micro-characters never appear in the case of copying and hence the invention is more reliable and safer. Preferably the micro-characters are 0.2 point or less in size. Further formation of a lathe or scroll work-pattern in the transfer portion has a better effect on the prevention of falsification.
In the invention of Japanese Patent Application No. H10 (1999)-185354, other than the micro-characters and the lathe or scroll work-pattern, a fluorescent latent image is preferably formed by using materials which absorb light in the range of wavelengths of non-visible light including ultraviolet rays and infrared rays, especially materials which absorb light in the ultraviolet ray range. In the case where the fluorescent latent image is formed in the transfer portion, if the transfer portion is released from the transfer-receiving material with the intention of falsifying particulars printed on the transfer-receiving material, the fluorescent latent image is also broken. When a fluorescent latent image is formed on the transfer-receiving material, the adhesion of the surface of the transfer-receiving material does not become uniform and hence the transfer failure and adhesion failure of the transfer portion tend to be caused. If a fluorescent latent image is formed on the transfer portion of the intermediate transfer recording medium, such a problem is not posed.
However, in such an intermediate transfer recording medium, the joints formed in a processing of a hologram pattern, that is, the joints between hologram patterns at which a hologram pattern ends, when a hologram pattern is processed one after another, appear at constant intervals. Since an image is formed on the receptor layer of the intermediate transfer recording medium without any consideration given to avoid such a joint between hologram patterns, in some cases, an image is formed on the joints between hologram patterns.
When the intermediate transfer recording medium on which an image is formed in this manner is used to produce a printed product, the joints between hologram patterns are found in the image. The resulting printed product is thereby reduced in product value and hence the use of such an intermediate transfer recording medium is undesirable, particularly in the case of producing printed products such as passports for which high reliability and safety are required.
In order to solve such a problem, the applicant has made a trial to prevent an image from being formed on the joints of hologram patterns by forming a detection mark, for setting the position where an image is to be formed, on each individually formed hologram pattern and by detecting the detection mark.
However, if the detection mark is formed by, for instance, printing or ink-jetting in the processing of a hologram pattern, an apparatus for printing the detection mark must be incorporated in a step of processing a hologram pattern. This renders the process complicated, giving rise to many manufacturing problems which are probably a cause of increased cost.
Also, if the detection mark is formed by, for instance, printing and the like after a hologram pattern is processed, the step of processing the hologram pattern is separated from the step of forming the detection mark. There is the case where the problem is posed that the intermediate transfer recording medium is elongated in the step of forming the detection mark so that the position of the hologram mark is not constant relative to the position of the detection mark and hence there is the case where the detection mark is not formed on the exact position where it must be formed. In the case of forming a complicated hologram pattern in particular, the inconstant position of the hologram mark relative to the position of the detection mark probably affects the positional relation between the hologram pattern and the image in the subsequent formation of the image on the intermediate transfer recording medium. Also, in an actual operation, the formation of the detection mark in a separate step is undesirable because it makes the manufacturing step complicated, which is a cause of increased cost.
A first object of the present invention is to provide an intermediate transfer recording medium provided with a hologram mark to set the position of an image to be formed, a method for forming a printed product by using the intermediate transfer recording medium and a printed product formed by such a forming method, thereby solving the aforementioned problem concerning the alignment of the intermediate transfer recording medium.
The intermediate transfer recording medium has other problems also. The peelable layer of the intermediate transfer recording medium is formed for the purpose of peeling the transfer portion from the substrate film with ease to improve the effect of transferring the transfer portion to the transfer-receiving material. The peelable layer is usually formed of a resin, such as polymethacrylates and polyacrylates, having a molecular structure of an acrylic skeleton. The peelable layer is improved in transfer efficiency with the peeling ability thereof from the substrate film. Hence, it is desirable that the peelable layer adhere to the substrate film with necessary and minimum adhesive strength. On the other hand, if the adhesive strength between the peelable layer and the substrate film is excessively weak, excessive extension of the transferred portion, such as tail-extension or burr is caused. Therefore, a polyester resin such as polyethylene terephthalate is usually contained in the peelable layer to adjust the adhesive strength to the extent that the peelable layer is supported in moderation by the substrate film.
In the meantime, the intermediate transfer recording medium has come to be provided with multi-layers including a protective layer and an ultraviolet absorbing layer or the like between the receptor layer and the peelable layer in response to recent diversified demands. The thickness of the transfer portion to be transferred to the transfer-receiving material has come to be very thick.
Since such an increase in the thickness of the transfer portion makes it difficult to cut (namely, difficult layer-cuttability) the transfer portion at the boundary between the portion to be transferred and the portion whose transfer is not required, the transferred portion is accompanied by a part of the portion whose transfer is not required, causing transfer failures such as tail-extension or burr. Moreover, the tail-extended portion and the burred portion fall down from the printed product during conveyance within the printer and adhere to products which are thereafter conveyed, causing product failures such as dusty products.
A second object of the present invention is to provide an intermediate transfer recording medium which controls the force required to separate a transfer portion from a substrate film (hereinafter called "peeling strength") so that the transfer portion on which an image is formed can be transferred without transfer failures while the transfer efficiency of the transfer portion is maintained.